1. Technical Field
The present disclosure relates to treating an open wound by applying negative pressure to the wound, and, more particularly, to a portable wound therapy system including a valve mechanism that allows the portable wound therapy system to operate continuously.
2. Discussion of Related Art
Wound closure involves the migration of epithelial and subcutaneous tissue adjacent the wound towards the center and away from the base of the wound until the wound closes. Unfortunately, closure is difficult with large wounds, chronic wounds or wounds that have become infected. In such wounds, a zone of stasis (i.e., an area in which localized swelling of tissue restricts the flow of blood to the tissues) forms near the surface of the wound. Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only receive diminished oxygen and nutrients, but, are also less able to successfully fight microbial infection and, thus, are less able to close the wound naturally. Such wounds have presented difficulties to medical personnel for many years.
Negative pressure therapy, also known as suction or vacuum therapy, has been used in treating and healing wounds. Treating an open wound by applying negative pressure, e.g., reduced or subatmospheric pressure, to a localized reservoir over a wound has been found to assist in closing the wound by increasing blood circulation at the wound area, stimulating the formation of granulation tissue, and promoting the migration of healthy tissue over the wound. Negative pressure therapy may also inhibit bacterial growth by drawing fluids from the wound such as exudate, which may tend to harbor bacteria. This technique has proven effective for treating a variety of wound conditions, including chronic or healing-resistant wounds and ulcers, and is also used for other purposes such as post-operative wound care.
Generally, negative pressure therapy provides for a wound covering to be positioned over the wound to facilitate suction at the wound area. A conduit is introduced through the wound covering to provide fluid communication to an external vacuum source, such as a hospital vacuum system or a portable vacuum pump. Atmospheric gas, wound exudate, or other fluids may thus be drawn from the reservoir through the fluid conduit to stimulate healing of the wound. Exudate drawn from the reservoir may be deposited into a collection canister.
Often, a negative pressure wound therapy device is carried or worn by the patient, including in public. Operation of the device may make the device intrusive and non-discrete. For example, the vacuum source may intermittently start or stop during operation to achieve and/or maintain a specific vacuum level at the wound. The intermittent starts and stops cause the therapy device to be intrusive on the patient and the resulting noise makes the therapy device non-discrete in public. As a result, the patient may become dissatisfied or non-compliant with wearing the therapy device. A reduction in negative pressure therapy duration may inhibit wound healing or cause the wound to become infected. One way to reduce the intrusive nature of the therapy device is to configure the therapy device to run continuously such that intermittent starts or stops and noise are eliminated.